I'll use a relatively recent occurrence as an example.

The state legislature in Kansas has a GOP supermajority, meaning that the GOP has all the power. After the recent census, they had to redraw the district maps to reflect changes in the population.

The city of Lawrence is one of the largest Democrat dominant areas in Kansas. When the GOP redrew the district maps, they cut Lawrence into four parts that combined with other areas. The end result of this is that instead of one Democrat dominant district surrounded by GOP dominant districts there are now four GOP dominant districts and no Democrat dominant ones. The way the map is drawn is clearly biased and ridiculous by any standard, but it serves to further cement the power of the far-right GOP in a state which, were the will of the people to actually be reflected, would be very moderate.